CHAPTER 9
Water Resources, Forests and Ecosystem Goods and Services
Among the ecosystem goods and services supplied by rainforests are numerous vital, but often
underappreciated, goods and services linked to
water resources. The Congo Basin forested region
forms part of the Congo Basin watershed that provides its inhabitants with multiple water-related
benefits, including water supply, flow regulation
and water quality. The watershed is characterized
by a dense river system that serves as an important
navigation system for Central Africa, plays a large
role in food supply and local livelihoods, acts as
habitat for a range of plants and animals and has
significant hydropower potential. In this chapter
we examine some of the goods and services provided by the hydrological system in the Congo
Basin and explore the relationship between forest
ecosystems and the water resources that provide
these benefits. A flexible spatial definition will be
applied; the primary focus is on the Congo Basin
forested region, but some consideration is given
to the entire Congo River Basin and to major
coastal cities on rivers outside the hydrological
basin that benefit from hydrological goods and
services. The chapter begins with an overview of
the water system in the Congo Basin, presents a
synopsis of select hydrological goods and services,
© Reto Kuster
Randall Brummett, Charles Tanania, Albert Pandi, Julie Ladel, Yolande Munzimi, Aaron Russell, Melanie Stiassny,
Michele Thieme, Sue White, and Diane Davies
describes the relationship between forests and water resources in large river systems and concludes
with a section on the state of knowledge and water resource management in Central Africa.
Photo 9.1: The forest plays an
important role in maintaining the quality and quantity
of water in the Congo Basin.
The Congo Basin Hydrological System
The forests of Central Africa overlap with
several major basins (figure 9.1): the Congo, the
Ogooué, the Sanaga, the Cross, and the lower Niger. There are also many smaller basins that drain
into the Gulf of Guinea.
The Congo River basin, with annual renewable water resources of about 1.3 billion cubic
meters, is the largest of these basins and accounts
for about 30 % of the water resources in Africa
and was estimated to contain a population of approximately 77 million inhabitants in 2005 (African Development Bank, 2006). It is the largest basin in Africa with an area of approximately
4 million km2; the Congo River has an annual
average discharge at Brazzaville of about 41,000
m3/s (Nkounkou and Probst, 1987). The Basin
includes portions of ten different countries, but
85.3 % of the Congo River basin falls within the
largely forested regions of four countries: Cameroon, Central African Republic, the Democratic
Republic of Congo and the Republic of Congo.
Within the Basin the hydrological network is very
dense and includes a complex river network, vast
inundated forests and lakes.
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Sources: WWF, USGS, SDSU, UMD, Tom Patterson,
US National Park Service.
Figure 9.1: Congo Basin Hydrological Watersheds
The Basin extends from latitude 09°15’ N in
the Central African Republic to 13°28’ S in Angola and Zambia, and from longitude 31°10’ E at
the Great African Lakes in the East African Rift to
11°18’ E on the Atlantic Ocean. The waters of the
Congo River originate in the highlands (1,400
m) and mountains of the East Africa Rift, as well
as Lake Tanganyika and Lake Mweru (Shahin,
2002) and flows north towards Boyoma Falls. The
Upper Congo (Lualaba River) ends at Boyoma
Falls where the Middle Congo begins. After the
town of Kisangani, the Congo River turns west
and southwest following a great curve. The Middle Congo ends at Stanley Pool, where the capital cities of Kinshasa and Brazzaville are located
(figure 9.2). There, the river expands some 24 km
across and the waters slow down considerably. Between Kinshasa and Matadi, a distance of about
350 km, the river descends some 280 m in elevation and is interrupted by numerous stretches of
rapids, the largest and most well known of which
are the Inga rapids. The River reaches the Atlantic
Ocean between Banana Point in the Democratic
Republic of the Congo, and Sharks Point in Angola, from where it continues its course underwater. The length of the Congo is approximately
4,700 kilometers. The major tributaries are: the
Luapula and the Lualaba (the two headstreams),
the Lomami, Ruki-Tshuapa and Oubangui (the
main navigable tributaries of the Congo), the
Sangha, and the Kasai.
In the central Basin there are vast areas of
flooded forests, characterized by brown humic
(acidic) waters that fluctuate with rainfall and
seasonal changes in the Congo River level. Figure
9.3 shows the extent of flooded forest in the central Congo Basin.4
The Congo River system covers three different
climate zones, including an equatorial zone with
tropical zones to the north and south and a more
temperate zone in the elevated region to the east.
The heart of the Basin is within the equatorial climate zone where there is no real dry season. The
rainfall in the equatorial region varies between
1,500 and 2,000 mm a year, with an average temperature of approximately 26º C. Average humidity is around 77.8 % and evapotranspiration is
around 1,700 mm.
Source: NASA.
Figure 9.2: Image of the Congo River at Stanley Pool. Taken from the International
Space Station on June 6, 2003
4
Data used in mapping the extent of flooded forests include:
Landsat TM and ETM+ imagery, JERS-1 SAR and SRTM.
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The flow of the Congo is influenced by a complex series of factors across the Basin, but overall
the Congo is more constant than many other African rivers because large sections of the watershed
lie above and below the equator, in the path of the
Intertropical Convergence Zone. However there
is some inter-annual variability with December
being the month of maximum flow and July and
August the months of lowest flow. The tributaries from the South, such as the Kasai, have two
periods of low water and two of high water each
year, but the tributaries from the north, such as
the Oubangui, have a single peak causing the regime of the main river to vary from place to place
(Shahin, 2002).
Since 1960 there has been a general decrease
in flow which coincides with a reported decrease
in precipitation from major meteorological stations.
Box 9.1: Wetlands Likelihood in the Cuvette Centrale
A new approach to mapping the wetlands of the Congo Basin has been applied to a 1,175,918 km2 region centered on the Cuvette centrale of the Congo Basin watershed. Mapping challenges include data limitations, vegetative structural heterogeneity, wetland
seasonal variability, and limited opportunities for data collection for ground-based training and validation. To overcome these limitations, a multi-source statistical supervised classification approach was undertaken. Passive optical remotely sensed imagery provided by
the Landsat Thematic Mapper (TM) and Enhanced Thematic Mapper Plus (ETM+) sensors, JERS-1 active radar L-band horizontal
co-polarization imagery, and 3 arc-second elevation data derived from the Shuttle Radar Topography Mission (SRTM) were used as
inputs. These data were related to wetland/non-wetland training data through a classification tree algorithm to yield a wetland probability map for the central Congo Basin. Wetland probability was expressed at a spatial resolution of 57 meters. The proportion of
wetland cover for the study area equaled 32 %, equivalent to 359,556 km2. Figure 9.3 shows the results of the study and the fine-scale
variation of central Congo Basin wetlands. The unique ecological characteristics of humid tropical forest wetlands merit their mapping
and monitoring. Improved wetland mapping can be used by a variety of applications, including hydrological modeling, forest use planning and biodiversity assessments. Future efforts will extend the method to cover the entire Congo Basin and to develop approaches
for quantifying changes in wetlands extent over time.
Source: SDSU and CARPE.
Figure 9.3: Wetland likelihood map for the
central Congo Basin area.
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© Guenay Ulutunok - GTZ
Photo 9.2: Rainfall is abundant and supplies rivers with large quantities of water.
Hydrological Goods and Services in the Congo Basin
© Alain Billand
Among the ecosystem services provided by forests in the Congo Basin are hydrological services
related to water resources, including the vast Congo River system. Following the classification used
by the Millennium Ecosystem Assessment, these
services can be categorized into: (1) provisioning
services - for example services related to water
supply, that can be used through extraction, for
purposes such as agriculture and municipal water
supplies, and in situ, for maintaining freshwater
fish production, navigation or hydropower generation; (2) regulating services, including services
that help to maintain biophysical processes; (3)
cultural services; and (4) supporting services, such
Photo 9.3: Navigation is
important in Central Africa,
but is sometimes interrupted
by waterfalls.
as maintaining biodiversity habitat. Hydrological
services also include water mitigation services that
diminish flood damage, stop in navigation due to
low waters, sedimentation of water bodies, saltwater intrusion and dryland salination.
In this section we review several of the provisioning and supporting hydrological services in
the Congo Basin, including: navigation, fisheries,
hydroelectric power generation, and biodiversity
habitat. This section does not review all the ecosystem services provided by water resources in the
Congo Basin, but instead serves as an introduction to some of the services of most immediate
concern for human populations.
Navigation
Within the Congo Basin, waterways provide
a dense navigation system that extends for over
12,000 km and supply a vital means of transportation within and between different countries in
the region. This network is the primary means of
exchanging goods and services for the bordering
communities and is the basis for a regional multimodal transportation network extending outward
from the main ports of Pointe-Noire, Matadi,
Brazzaville, Kinshasa, Bangui, and Kisangani (figure 9.1).
In the colonial era, rivers were used to transport goods and passengers between the Atlantic and the interior. To bypass the un-navigable
falls and rapids three portage railways were built:
Matadi to Kinshasa, Pointe-Noire to Brazzaville
and Ubundu to Kisangani. All were abandoned
at some point due to sabotage and civil war. Since
1997, periodic suspension of the Congo-Ocean
Railway, linking Brazzaville to Pointe-Noire led
traders to use an overland route through Cameroon. Limited freight and passenger services
were resumed in 2000 and 2001 and restoration
of the line is being discussed. The line between
Matadi to Kinshasa does not work and the line
from Ubundu to Kisangani has long since been
reclaimed by the forest (Butcher, 2008).
With outdated railways and relatively few
roads, the complex system of waterways is vital
for local economies throughout the Congo Basin
and the revival of the regional economy. Inland,
the Congo and the Oubangi rivers form the two
main axes suitable for commercial traffic and yet
despite the importance of these waterways river
traffic has severely decreased. This is partly due
to political instability and a decrease in water
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In general the navigation system in the Congo Basin suffers from significant problems: poor
maintenance, insufficient beaconing of waterways, modest traffic, lack of regulation, out datedness and insufficiency of transport facilities, as
well as additional non physical barriers. Managing
navigation on shared waterways is a key objective
for CICOS, the International Commission for
the Congo-Oubangui-Sangha (box 9.2).
© Frank Ribas - GTZ
level on the Oubangui over the last 30-years. The
Service commun d’Entretien des Voies navigables
(SCEVN) noted an 18 % decrease in discharge
since 1985 (figure 9.4). Shallow water levels on
the Oubangui River during the dry season prohibit the use of barges for navigation for five
months of the year. When water levels are sufficiently high it takes approximately 21 days for
a convoy of barges carrying about 1,500 metric
tons to complete the 2,360 km round trip from
Bangui loading either in Kinshasa or Brazzaville
and back to Bangui.
Box 9.2: CICOS - International Commission for the Congo-Oubangui-Sangha
On November 17, 1999, CICOS, the International Commission for the Congo-OubanguiSangha Basin, was created to strengthen trans-border management of water resources between the
four riparian countries which together compose 85.3 % of the Congo’s hydrological basin: DRC,
Cameroon, Republic of Congo and CAR. The original Accord, ratified by the four Heads of State,
identified internal navigation as the key objective. On February 22, 2007 an amendment to the Accord supporting the Integrated Management of Water Resources (IWRM) was ratified. The overall
aim of CICOS is to manage water resources based on shared strategies that promote trade and economic development, while also controlling pollution and adhering to IWRM principles.
The institutional framework of CICOS is composed of two bodies: (1) the Ministerial Committee, which serves as the decision making body of CICOS and (2) the Management Committee,
which acts as the advisory body or steering committee.
Photo 9.4: Water is a basic
necessity; its quality is preserved by the forest.
© Omari Ilambu - WWF Salonga
140
120
Number of days
100
80
60
40
Photo 9.5: A “residential”
boat on the Salonga River in
DRC.
20
0
Years
Source: Ladel et al., 2008.
Figure 9.4: Number of days with a water height of less than 90 cm required for an economic navigation on
the Oubangui River.
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Fisheries and Livelihoods in Congo Basin Rivers
Estimates of annual fish catch from the
Congo Basin vary widely and range as high as
120,000 metric tons. In addition to generating
the majority of animal protein consumed by rural
communities, the value of the catch represents an
important proportion of gross national income in
the rainforest zones. An estimated 20 % of the
adult population living in rainforests are engaged
in river fisheries (Brummett and Teugels, 2004).
Actual fish yields and their value are unknown but
the potential for the fishery in the mid 1980’s was
estimated at 520,000 tons worth $ 208 million
(Neiland and Béné, 2008). Chapman and Chapman (2003) estimate that this value represents
only 41 % of the potential total catch in DRC.
There is very little actual or published data
on the Congo Basin fisheries. The following descriptions are summarized from an ongoing research by the World Fish Center (funded under
CARPE) in lakes Tumba and Mai-Ndombé, the
Salonga River and the Lomako River.
The Fishery
The most widely used gear is the traditional
basket trap. These come in a wide range of lengths
from 30 cm up to 3 m or more. These are placed
in streams and shallow sections of main rivers at
fish migration routes. They are held in place with
stakes, rarely baited and checked daily for fish.
Such traps are cheap, being mostly manufactured
by the fishers themselves.
A widespread women’s traditional fishery or
“écoupage” is also based on home-made baskets
used as the waters recede from the forest during the dry season to capture small and juvenile
fishes, crabs and freshwater prawns. The “epoko”
is a small, nearly watertight basket that is used to
bucket water out of depressions in the swamp forest or from small dams constructed on low-order
streams. Usually, 6-10 women, lead by an older
and more experienced matron, will work together
to share the work.
The most widely used “modern” gear in the
commercial (all male) fishery is the “Lubumbashi”
style gill net, named after the defunct fishing net
factory that produced netting up until 1983. Gill
nets are generally placed in parallel with the river
current across entry/exit points where fish move
between the main river and the flooded forest.
Hooks are comparatively rare among the typical fisher, but “professional” fishers (see below)
report using baited hook-lines for the preferred
Parachanna obscura (“mongusu”) an ambush predator difficult to catch with set nets.
The use of dynamite, chemical poisoning of
ponds and burning vegetation have been reported
as illegal fishing methods in Salonga National
Park (Inogwabini, 2005).
Out of some 1,000 estimated species in the
Congo river system (Thieme et al., 2005), only
50 are regularly captured. Due to the inability of most fishers to access deep water or main
river channels, many of these are taken only as
juveniles while they are feeding and growing in
the flooded swamp forest or during (horizontal)
spawning migrations between the main river and
the flooded forest.
The Fishers
Most fishing occurs during the dry season
when the water is relatively low, the swamp forest is relatively dry and fish are concentrated in
the rivers. However, some fishing, especially for
household nutrition, occurs throughout the year.
During the peak fishing seasons, groups of fishers
operate from small villages or temporary camps.
Fishing is seen as a complimentary activity to agriculture. Most fishers remain dependant upon a
larger village where they cultivate land for agriculture.
Despite well-known village boundaries, the
fishery is open-access with people fishing pretty
much wherever they please. Most fishers are, nevertheless, from the village on whose land they are
situated, which permits them to retain traditional property rights to any agricultural plots they
manage. All of the interviewed fishers insisted
that newcomers are welcomed and that there are
no constraints put on fishing access and no requirements to seek permission from traditional
authorities.
Fishing is seen as a complimentary activity
to agriculture and many fishers are only fishers
because of a lack of capital and markets needed
to undertake traditional agriculture on a larger
scale. When asked specifically what they would
do if they had “enough money,” fishers indicated
that they would go back to the village, build a
house and obtain a plot of land to farm. These
fishers operate an average of about 13 nets (approximately 50 m wide) and a few dozen hooks
and manage to capture 20-30 valises (3-5 kg) of
dried fish per year.
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The Fishery Value Chain
It is estimated that fishers keep about 1 kg per
family (avg ~6 persons) per day for household
consumption. The rest is destined for market.
These are usually smoked in a single layer over an
open hot fire using dry wood for a period of about
6 days. This results in a product that is charred on
the outside but poorly preserved on the inside.
The typical practice is to store these fish throughout the dry (fishing) season until prices rise in the
following rainy season, meaning that most fish
are held for at least 2-3 months, and sometimes
up to 6 months prior to marketing. Smoking is
often repeated monthly during storage to combat
insect infestation and mould. The process leads to
dry matter losses estimated by the fishers at between 30 and 50 %.
Salting and sun drying produces a higher
quality product, but relies on expensive salt that
has to be brought in from either Kisangani or
Basankusu. The high cost of salt, approximately
10,000 Congolese Francs per 20 kg (roughly $ 20
in 2008), encourages fishers to try to brine their
fish in lower-than-optimal concentrations, reducing quality. Although the data collected on fish
are sparse, observations indicate that the relative
return on salted fish has the potential to be double that of smoked fish, and may possibly surpass
that of fresh fish due to its longevity.
The catch from the women’s écoupage fishing is primarily consumed by the household, but
in times of abundance may be marketed locally.
Women are heavily involved in the smoking of
the men’s commercial catch, cleaning the fish,
gathering firewood and tending the fires. In the
“professional fisher/trader” camps, all processing
and trading is done exclusively by the women,
leaving the men to spend more time fishing.
Fish are marketed in a variety of baskets and
basins. The smallest unit is the “valise” which
holds about 30 smoked fish (estimated 5 kg dry
weight, 10-20 kg wet weight). A “basket” contains
5-6 valises while a “suzuki” in turn holds some 3-4
baskets. None of the above units are standardized,
so one often hears of a “small valise” or a “large
suzuki.” Salted fish are transported on open “paniers” that hold roughly 10 fish. Écoupage catches
are transported either in the small epoko used in
the écoupage, but more frequently in large baskets
called “corbeilles” that equal roughly four epoko in
volume. In more accessible camps fish can be kept
alive for several days in 15 L plastic basins for sale
as fresh fish, and contain between 120-140 fish.
Price is a function of the size of the unit, species
and condition of the fish.
From a study in Basankusu a valise of the
most valuable species, P. obscura (“mungusu”) in
good condition sells for about 3,000 Congolese
Francs (roughly $ 6). At the other extreme, the
least preferred Malapterurus sp (“neena”) in bad
condition sells for about 1,000 Congolese Francs
per valise ($ 2). Overall, prices vary by 30-50 %
according to the state of the fish and supply in
the market.
© Frank Ribas - GTZ
There are a minority of fishers who are considered professionals. These people usually bring
manufactured goods (e.g., clothing, sandals, mosquito nets, torches, batteries, fishing gear) from
outside to barter for fish as well as doing their
own fishing. The typical professional fisher operates about 100 nets plus 1,000-1,500 hooks and
catches 60-100 valises per year. Once they have
enough fish to fill their pirogue, they go to town,
sell their catch, replenish their supply of consumer goods and return. These trader-fishers tend to
move around and compete with each other for a
presence in the best fishing camps.
Photo 9.6: The waters of
Central Africa are rich in fish
species.
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Table 9.1: Indicative enterprise budget (in Congolese Francs*) for a fishing family
working the two main fishing seasons on the Lomako River
Nets
Transport
Food and
accommodation
“Taxes”
Total cost
Fish sales
Profit/loss
Low market
Unit price
Total
3,000
39,000
7,000
14,000
500
4,200
High market
Unit price
Total
3,000
39,000
7,000
14,000
500
4,200
Quantity
13
2
14
Units
50-m
2 oarsmen
days
25
valises x 2
ports
2,000
50,000
2,000
50,000
25
valises
2,500
107,200
62,500
-44,700
5,000
107,200
125,000
17,800
Exchange rate $ 1 = 500 Congolese Francs
As markets can be distant and expensive to
reach, marketing tends to be opportunistic. It
has been reported that many fishers sit in their
pirogues along the main channel waiting to sell
small quantities of fresh fish, or occasionally valises of smoked fish to passing boats. A minority of
fish is sold this way, most likely to the professional
fisher-traders.
Most fishers choose to go to market when they
need money or when the fishing is poor, rather
than waiting until there are enough fish to make
a full load. This means that most of the fishers
travel to markets around the same time, after the
end of the dry season, when the fishing starts to
get worse, and when people need money to invest
in clearing land for farming.
Overall, lack of market access, poor quality
and illegal taxes levied arbitrarily by government
officials render fishing a subsistence activity. Under the right conditions, aquaculture could make
a significant contribution to food security and
economic growth (Brummett et al., 2008).
Hydropower Potential
http://www.mbendi.com/indy/powr/
af/co/p0005.htm (accessed 24 Feb.
2009)
6
http://www.fwt.fichtner.de/php/
main/page/php/referenzen.php/
ukat_id/6/kat_id/3/idc1/27/z1/2/
map/1/sprache/e/li/0re (accessed 24
Feb. 2009)
5
The varied hydrological arrangement associated with the topology of the river courses in the
Congo Basin offers numerous opportunities for
hydropower development. At the end of 2005,
most of the installed capacity for generating electricity in the Congo Basin was from hydropower.
The total installed operational capacity of hydropower was reported at 6,490 MW, 39 % (2,540
MW) of which is located in DRC (see table 9.2).
The installed capacity represents only a small
fraction of the estimated hydropower potential in
the Congo Basin. Studies examining the potential
for hydropower generation, point to the Congo
Basin, and the Inga rapids in particular, as the
most important potential source of hydropower
development on the African continent. Currently, the Inga hydropower station comprises a
358 MW plant (Inga I) that was commissioned in
1972 and a 1,424 MW plant (Inga II) that began
operating in 1982 (both are currently reported to
be operating at less than half their installed capacity). The overall hydropower generating capacity
of the Inga site has been estimated at 44-60 GW
and the interest to build a third Inga site (Inga
III) and develop a pan-Africa electricity exporting project has long existed. Plans are currently
underway with Westcor (Western Power Corridor
(PTY) Limited) to begin construction for Phase I
of Inga III in 2010, with full commissioning of
Phase I anticipated in 2015 at a base power of
5,000 MW. An ambitious undertaking, this project is at the center of the NEPAD Infrastructure
Program and represents a serious potential source
of revenue for potential shareholders, including
an estimated $ 424 million annually for the government of DRC after payment of capital debts
during years 1 to 5. Revenues are expected to increase to $ 594 million and finally to $ 678.8 million in subsequent years (Westcor, 2008).
Other hydropower (proposed and actual) developments of note are:
• The Imboulou hydropower dam on the Léfini
River in the Republic of Congo. Construction
of the facility began in 2005 and was expected
to take 5 - 6 years. It is expected to have an
installed capacity of 120 MW.5,6
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Table 9.2: Hydropower capacity in the Congo Basin at the end of 2005
Net installed capacity of electric generating plants
Angola
Burundi
Cameroon
CAR
ROC
DRC
Gabon
Rwanda
Tanzania
Zambia
Total
Total (all types)
MW
525
33
875
43
93
2,573
420
39
549
2,260
6,990
Hydropower
MW
390
32
805
22
92
2,540
175
35
329
2,245
6,490
Production of hydropower
electricity.
MWH
1,747
99
3,913
84
355
7,395
814
130
1,778
5,834
21,335
Source: United Nations, 2005. All figures are estimates by the Statistics Division of the UN Secretariat.
• The Belinga dam, Gabon. The Kongou Falls,
on the Ivindo River have been earmarked as the
site for this dam (Stella, 2007). The proposed
Belinga dam would generate power for the Belinga Iron Ore Project. Environmental groups
are concerned that if the dam is constructed
at the Kongou Falls in Ivindo National Park,
it will have a negative impact on the biodiversity and natural resources and have requested
the dam be moved instead to Tsengué-Lélédi
Falls. Civil society groups are also concerned
about the imbalance of benefits for the Gabonese people. Currently Gabon’s primary hydropower sites are located at Tchimbélé, in Monts
de Cristal National Park (69 MW) (supplying
electricity to Libreville) and Kinguélé (58 MW)
on the M’Bei River.7
• The Ruzizi III dam in DRC would be situated
25 km downstream from Ruzizi I and II, already located at the outlet from Lake Kivu. Ruzizi I and II are operated by a tri-national company (Burundi, Rwanda and DRC). Electricity
production is insufficient to meet the needs of
the adjacent areas. A further dam, Ruzizi III, is
planned to meet the shortfall
• The Lom Pangar dam in Cameroon. The two
main hydro stations, Song-Loulou (384 MW)
and Edéa (264 MW) located on the Sanaga
River, have experienced significant reductions
in power generation due to reservoir sedimentation, poor maintenance and dry seasons exacerbated by drought (Hathaway and Durrell,
2005). Construction of the Lom Pangar dam
would help regulate flow of the Sanaga and increase and secure constant power output from
two downstream dams. This would be the
fourth dam built to help regulate the Sanaga
River. The project has been delayed due to pressure from environmental groups who claim it
will submerge part of the Deng Deng Forest
Reserve, a refuge for endangered animals such
as chimpanzees, elephants, gorillas, and black
rhinoceros. Concern has also been expressed
about Cameroon’s heavy reliance on hydropower when drought is already an issue.8,9
Climate models for Africa are far from clear
(Schiermeier, 2008) and so too are the effects that
climate change will have on large hydropower
schemes. Mukheibir (2007) is of the opinion that
an increase in the average annual rainfall in the
Congo Basin would lead to increased generation
potential but notes this could also have negative
impacts of increased flooding and associated large
sediment loads which would be detrimental to
large dams. By contrast Paeth and Thamm (2007)
modeled climate scenarios for Africa and indicate
that there could be a reduction in precipitation in
the Congo Basin by up to 500 mm (20-40 % of
the annual sum) which could seriously limit the
hydropower potential of the region.
Although Africa’s great rivers are considered
“under-dammed” by global standards, many of
the big dams constructed have been built at the
expense of rural communities and important ecosystems. In response to such concerns, guidelines
and improved practices for decision making and
risk assessment have been put forward by the
World Commission on Dams and the Dams and
Development Project.10
http://www.internationalrivers.
org/en/africa/belinga-dam-gabon
(accessed 24 Feb. 2009)
8
http://africanpress.wordpress.
com/2008/02/02/delay-inconstruction-of-lom-pangardam-slows-project-to-upgradealuminium-smelter/ (accessed 24
Feb. 2009)
9
http://www.internationalrivers.
org/en/africa/drought-couldcripple-cameroon %E2%80%99shydro%E2%80%93heavy-energysector (accessed 24 Feb. 2009)
10
http://www.dams.org/.
7
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Freshwater Biodiversity and Habitats
The forested region of Central Africa is characterized by a large diversity of freshwater system
types and habitats, from the large delta of the
Niger River, to the extensive swamp forests and
associated lateral lakes of Central Congo, to the
powerful rapids of the Lower Congo, to the web
of marshes and lakes along the Upper Lualaba.
Several authors have defined freshwater biogeographic provinces for Africa based on freshwater fish (Lévêque, 1997; Roberts, 1975; Thieme et
al., 2005). Each province encompasses freshwater
systems sharing a relatively similar fish fauna. The
boundaries largely correspond with the catchments of major river systems, which provide the
natural routes for gene flow for freshwater fishes
(Stiassny et al., 2007). The major ichthyofaunal
provinces in the region are the Congo, Lower
Guinea, and Nilo-Sudan. These provinces are
further subdivided into freshwater ecoregions,
which also largely follow river basin divides and
are intended to describe broad patterns of species
composition and associated ecological and evolutionary processes (figure 9.5; Abell et al., 2008;
Thieme et al., 2005).
The diversity of habitats in the region is
matched by high species diversity. However,
taxonomic surveys are lacking for much of Central Africa and new species are continually being
discovered (Lévêque et al., 2005; Lundberg et al.,
2000). For fish species, it is considered the third
richest tropical river basin, following the Amazon
and Orinoco Basins. Over 550, 700, and 150 fish
species are currently described from the Lower
Guinea, Congo, and Niger Delta, respectively;
with new species being described every year (Stiassny et al., 2007; Teugels and Guégan, 1994; Thieme et al., 2005). The rivers and streams of Lower
Guinea and the Congo have high levels of fish
endemism (estimated at 50 % and 80 %, respectively). About fifteen strictly aquatic mammals
live in the waters of Central Africa; including several that are endemic (e.g., the aquatic genet (Osbornictis piscivora), Ruwenzori otter shrew (Micropotamogale ruwenzorii), and giant otter shrew
(Potamogale velox)). The region also has a rich
herpetofauna – upwards of 280 aquatic frogs, and
about twenty aquatic snakes, turtles and crocodiles are known. Data on aquatic invertebrates are
particularly scarce; however, available data suggests that the region harbors areas of high invertebrate biodiversity. Kalkman et al., (2008) identified the Guinean-Congolian region as having the
greatest diversity and number of range-restricted
species of Odonates (dragonflies) in Africa. The
richest areas for dragonflies are the Cameroonian
highlands and Lower Guinean lowland forests
(Kalkman et al., 2008). Diversity of freshwater
crabs appears to be highest in the lower parts of
the Congo Basin and the upper reaches, including those draining from Rwanda and Burundi
(Groombridge and Jenkins, 1998). Southeast Nigeria, southern Cameroon, and Gabon also host
three endemic genera and more than 10 endemic
species of freshwater crabs (Cumberlidge, 1998).
Aquatic mollusks are very poorly known - about
100 snails (gastropods) have been described from
the Congo Basin, of which about half are considered to be found only there (Brown, 1994);
a contemporary region-wide estimate of aquatic
mussels does not exist, though there are historical
and more recent syntheses for parts of the region
(e.g., Graf and Cummings, 2006; Pilsbry and Bequaert, 1927).
Despite the lack of reasonably comprehensive
georeferenced species data, several studies have
highlighted freshwater biodiversity hotspots in the
region (Groombridge and Jenkins, 1998; Kamdem-Toham et al., 2003; Thieme et al., 2005).
Common among these are the Lower Congo rapids for their rheophilic and endemic fish and mollusks; the Cuvette centrale and associated marshes
and swamp forest for high fish richness and endemism; floodplain lakes and marshes of the plateau
region of the Upper Lualaba for fish endemism;
several crater lakes in Cameroon with highly endemic aquatic faunas; several rivers of the Lower
Guinea province including the Ogooué, KouilouNiari, and Cross Rivers for high richness and endemic fish and crabs; and the Niger Delta with
five monotypic fish families. Additional areas will
be added and the boundaries of existing hotspots
will be modified as new data on the biodiversity
of the region become available.
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Sources: WWF, TNC, SDSU, CICOS.
© Robert Nasi
Figure 9.5: Freshwater ecosystems
Photo 9.7: Riparian forests have specific floral compositions.
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Box 9.3: The Lower Congo River
In 2005 the American Museum of Natural History’s Congo Project received funding from the US National Science Foundation to
undertake an ichthyofaunal survey and inventory of the lower Congo River (http://research.amnh.org/ichthyology/congo/index.html).
The project which is an ongoing international, multidisciplinary collaboration is combining traditional taxonomy and survey methods
and the latest molecular techniques with state-of-the-art remote sensing technologies and in-situ geomorphological analysis. Results to
date reveal the lower Congo River to be a site of unexpectedly high fish biodiversity forged by an uniquely complex physical regime.
By integrating analyses of hydraulic conditions and channel morphology with metapopulational analyses of fish species in the lower
Congo the project aims to elucidate the underlying processes driving speciation and diversification in the river.
Near the twin capitals of Kinshasa and Brazzaville, the lower Congo River spills out over a rocky sill at the southern edge of Stanley Pool and cascades down through the gorges of the Crystal Mountains. This relatively short stretch of the river, fed by a discharge
of 23,000-50,000 m3/s is punctuated by some of the most spectacular rapids, pools and runs on Earth. Unlike most of the rest of
the river, the lower Congo downstream of Pool Malebo to the port town of Matadi, is highly channel-constrained with a peculiarly
complex hydrology that appears to have isolated it from the remainder of the Basin. Channel topology itself is highly heterogeneous,
punctuated by underwater canyons of extreme depth. Water velocities are also extreme, even in areas without surface rapids, and recent
measurements taken with pirogue-deployed Acoustic Doppler Current Profilers (ADCP) have revealed complex flow patterns within
the water column including shifting counter directional flows and descending and ascending “walls” of fast moving water. Analysis of
remotely sensed data provides an additional view of the numerous macrohabitats and channel features that characterize this hydrologically complex stretch of river. Using the latest remote sensing technologies, and with intensive on-the-ground sampling and analysis,
a much clearer picture is beginning to emerge of how the geomorphological template of the river has played a major role in isolating
fish populations.
To date the project has documented the presence of over 300 fish species and of these upward of 80 appear to be endemic to the
lower Congo region. These are unexpectedly high levels of species richness and endemism for a 350 km stretch of river, by way of
comparison the entire Upper Nile from its headwaters to the junction with the Blue Nile at Kartoum, a stretch well over 1,400 km in
length, harbors around 115 fish species of which only 16 are known endemics. Clearly the lower Congo, with its unique hydrological
regime, represents a model system for exploring the interplay of complex hydraulic conditions, channel features of extreme depth, and
patterns of species richness and drivers of local endemism.
Relationship between Forests and Hydrological Goods and
Services
Forest Cover and Watersheds
Water resources are regional services that are
strongly influenced by their ecosystem. Vegetation
is often the primary influence of these ecosystem
effects on hydrological services (Brauman et al.,
2007). In a forest ecosystem, forests influence the
hydrological cycle by regulating the quantity and
timing of water and nutrients being added to the
system. The extent to which ecosystems are affected is dependent on the size and distribution of
different ecosystems within a catchment system
as well as the frequency, duration and intensity
of climatic events. Andreassian (2004) argues that
larger forests, such as the Amazon or Congo Basin
play a critical role in both controlling the quantity and quality of water circulating in a watershed
or river basin as well as influencing climate at the
global level. In the following section we examine
local and regional interactions between forests
and water resources.
The Role of Forests in the Congo Basin Water Balance
Relative to other comparable forested regions,
far less research has gone into understanding the
relationship between forests and water in the
Congo Basin (box 9.4). However, studies from
other areas can provide insight into how forest
cover may affect water systems. The common perception is that “forests are good for water,” acting
like sponges to absorb high rainfalls and releas-
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ing water slowly through drier periods. While it
is generally accepted that forests improve water
quality, moderate peak flows and sequester carbon
dioxide, trees can also use more water than other
vegetation types and so the net water balance
may mean that less water is provided to downstream areas than for other land covers (Dudley
and Stolton, 2003; Bruijnzeel, 2004; Brauman
et al., 2007). This increased water use is due to
the larger rooting depth of trees (compared with
grassland or agricultural crops) allowing them to
access water from a greater portion of the soil profile, and sometimes even from the sub-soil. Forest
also presents a rougher surface than shorter crops,
thus increasing the efficiency of gas exchanges
with the atmosphere (Brauman et al., 2007).
Evidence of the greater water use of forests
has been accumulated mainly from studies where
forests have been cleared and net water supply has
increased, albeit in a much more irregular flow
distribution pattern. These studies are almost
exclusively for montane forests. No reported declines in annual streamflow totals following lowland tropical forest removal have been found in
the literature. For montane forests controlled experiments comparing water yield before and after
deforestation, show that in all cases the removal
of more than 33 % of forest cover results in significant increases in overall annual streamflow during the first 3-years, with changes in water yield
roughly proportional to the fraction of biomass
removed (Bruijnzeel, 2004). The reverse effect
has been observed: in a review of 14 comparative
experiments in the tropics to find that after afforestation or planting trees in agricultural fields
there was approximately a three-fold increase in
water infiltration. Elsewhere it has been shown
that afforestation will reduce local water yields
and flow, but these effects are likely to be small
unless the area reforested is large (Van Dijk and
Keenan, 2007). In studies on smaller tropical wa-
tersheds, deforestation has been shown to increase
discharge and runoff (Sahin and Hall, 1996).
Mature tropical rainforest deforestation has
the potential to degrade the regulation of hydrological flows through changes in evapotranspiration, canopy interception, surface runoff and
groundwater recharge. Reductions in evapotranspiration (the process of direct evaporation and
transpiration by plants that transfer water to the
atmosphere) with increasing deforestation can
impact hydrological flows by warming the surface, inhibiting convection and changing regional
precipitation and cloud cover. Most evidence of
these impacts has been witnessed in smaller river
basins, where in many cases the effects of land
cover change on hydrological processes are not
measurable until at least 20 % of a catchment has
been converted, although this threshold may vary
between 15 to 50 % (Stednick, 1996). The effects
of land conversion on evapotranspiration may be
less for conversions between primary and secondary forests, as opposed to cropland or shrub land.
The results of local, short-term studies provide
important information but can not necessarily be
extrapolated to the larger scales and time frames
of relevance when discussing vast river systems
like the Congo Basin. A study by Costa et al.,
(2003) in a large Amazonian river basin found
that changes in land cover had a significant impact on discharge, although not precipitation. In
the Congo, the effects of deforestation on rates
of evapotranspiration are expected to be particularly significant because a large portion of rainfall,
(between 75-95 %), comes from recycling moisture from the region’s forests (Brinkman, 1983).
A recent study mapping forest clearing over the
last decade for the entire Congo Basin (Hansen et
al., 2008), at a spatial resolution that allows forest
clearing to be examined on a per watershed basis, will provide important data for future studies
(figure 9.6).
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Sources: SDSU, USGS.
Figure 9.6: Watersheds with more than 50 percent forest cover in circa 1990 and a 5 percent loss in forest cover by circa
2000 are highlighted in yellow
Box 9.4: State of Knowledge
Compared to other vast river systems in the world, little information and research is available for the Congo Basin. Quantitative
data on water resources within the Congo Basin has always been limited. The collection and management of information on water
resources are difficult for numerous reasons, including:
• The dilapidated state, and low density, of data collection sites for hydrological, limnimetric or meteorological information.
• Few stations are operational, most are manual and they are usually limited to large freshwater areas.
• The discontinuity in the hydroclimatological data series in the vast majority of hydroclimatological stations across the Basin. Very
few continuous data sets, where continuous refers to constant data collection since pre-1960, exist. Even rarer are meteorological or
hydrological stations with a continuous series of data for the past 100 years. The data that is most frequently presented have been
collected through remote sensing.
• The lack of coordination between different sectors concerned with water resource management in all the riparian countries.
However some historic data are available for: the Congo from 1902 (station in Kinshasa), 1907 (station in Kisangani), and 1912
(station in Kindu); from 1911 for the Oubabgui (station in Bangui) and from 1948 on the Sangha river (at Ouesso). Daily water levels
are measured at Bangui, Ouesso, Brazzaville and Kinshasa. The three organizations charged with monitoring flow in the Congo Basin
are:
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• The Régie des Voies fluviales (RVF) in DRC for the middle and upper portions of the river.
• The Régie des Voies maritimes (RVM) in DRC for the lower Congo.
• The Service commun d’Entretien des Voies navigables (SCEVN) in CAR and ROC for the Congolese section of the River and the
Oubangui.
The African Monitoring of Environment for Sustainable Development program (AMESD; www.amesd.org/www.cicos.info) in
Central Africa aims to develop a monitoring system for water resources in the Congo Basin. Implemented by CICOS for Central Africa, AMESD will utilize existing meteorological satellite data receiving stations in seven Central African countries, install additional
environmental receiving stations in key organizations and built the capacities of regional experts with the aim of providing regular
information on water levels and the water cycle (rainfall, runoff and evapotranspiration will be measured) (Ladel et al., 2008). Two
operational services will be developed: one to alert on low waters for navigation, and one to monitor the impact of deforestation and
climate change, initially on the Oubangui sub-basin water resources.
Water Resource Management
The Congo Basin has abundant water supplies
and great potential to develop further in the areas
of hydropower, irrigation and navigation. In the
past a piecemeal approach to water management
focused solely on satisfying immediate demands
for energy, agriculture or urban water supply.
And in doing so it failed to take into account the
potential environmental, social or long-term financial impacts. Conflict, lack of regulation and
mismanagement has left more than half the rural
population in Congo and DRC without access
to clean drinking water and adequate sanitation
facilities11. The need to improve water management in the Basin is widely recognized both within individual countries and across the Basin as a
whole.
In response to this need, an Integrated Water Resource Management (IWRM) approach
has been adopted (box 9.5) by CICOS. This ap-
proach to planning and implementation simultaneously works to balance society’s long-term
needs for water, essential ecological processes and
economic benefits. It is centered on maintaining
the environment while also promoting sustainable development and encouraging democratic
participation in governance. A better understanding of the relationship between forests and water
resources, as well as an appreciation for the economic value of forests based on the water-related
services they provide (see box 9.6) can be used to
increase the incentive to maintain healthy forest
ecosystems and conserve forest watersheds. Although a comprehensive economic assessment of
the goods and services provided by water resources
has never been attempted in the Congo Basin, it is
clear that the economic value of water resources in
the Congo Basin and the dependence of human
populations on these resources are great.
11
http://www.unicef.org/
infobycountry/centralafrica.html
Box 9.5: Integrated Water Resource Management (IWRM)
The history of IWRM stems back to the United Nation’s Mar del Plata Conference in 1977 which called for increased coordination
between different sectors concerned with water management. In 1992, the International Conference on Water and the Environment
reiterated the need for a more holistic approach to assure the sustainable use of water resources. The 2000 Millennium Development
objectives called for IWRM to go further to incorporate interactions between surface water and underground water resources, as well
as taking into consideration the limits of the environment and managing the demand for water.
IWRM is a process that promotes the co-ordinated development and management of water, land and related resources in order to
maximize the resultant economic and social welfare on an equitable manner without compromising the sustainability of vital ecosystems. It is based on the following four Rio/Dublin principles:
1. Fresh water is a finite and vulnerable resource, essential to sustain life, development and the environment.
2. Water development and management should be based on a participatory approach, involving users, planners and policy-makers at
all levels.
3. Women play a central role in the provision, management and safeguarding of water.
4. Water has an economic value for all its competing uses and should be recognized as an economic good.
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© Carlos de Wasseige
Photo 9.8: The Congo River
in Kinshasa.
http://www.engineeringnews.co.za/
article/development-bank-fundsproject-to-support-management-ofcongo-river-2007-06-22 (accessed
24 Feb. 2009)
13
http://www.gtz.de/en/themen/
umwelt-infrastruktur/wasser/18950.
htm (accessed 24 Feb. 2009).
12
Understanding the role forests play in providing these benefits will support adopting an
ecosystem approach to managing forests that involves evaluating the “trade-offs” between alternative management schemes. This can be complex
because it is often difficult to assess the long-term
impacts of actions such as deforestation or carbon
sequestration on the ecosystem or the services it
provides (Foley et al., 2007; Jackson et al., 2005).
The variation in geographic scale of ecosystem services further adds to this complexity, with some
services extending to cover whole watersheds.
Additional research is needed to further explore
the intricate relationship between changes in land
cover and water resources in the Congo Basin,
specifically from the perspective of the goods and
services provided by water resources at different
space and time scales. In addition to local and
national governments there are two principal organizations concerned with managing the Congo
Basin’s water resources: CICOS (see box 9.2) and
the Authority of Lake Tanganyika.
CICOS recognizes that the management of
vast river basins is dependant on many factors,
including: the ecological nature of the basin, demographic and socioeconomic conditions, the
historical context of the Basin, partnerships, regulating texts and laws, the engagement of governments, financial factors and planning. Given all of
these different variables it is difficult to provide a
comprehensive strategy of resource management
for water resources in the Congo Basin; however,
CICOS has identified some underlying principles
that are necessary to implement effective resource
management:
• implementation of a political process of transboundary cooperation between all the riparian
countries;
• increased availability of pertinent data and information on water resources;
• application of institutional agreements for issues such as the division of costs, environmental regulations, environmental standards, etc;
• a clear definition of the role of the organization
in charge of Basin management;
• strong leadership within the governing organizations;
• strong implication of stakeholders, including
the public, in the development of management
plans and the implementation of policies.
With funds from GTZ and the African Development Bank12,13 CICOS has been tasked with
the preparation of a strategic action plan for integrated management of the Basin’s water resources.
As part of this plan activities are likely to include
the rehabilitation of an in situ hydrological network within the Basin (complementary with
the AMESD satellite monitoring system), the
creation of an information management system
within the CICOS Secretariat and capacity building to implement activities in accordance with the
principles and strategies agreed with the riparian
countries. It is hoped that this approach will promote well-coordinated policies at the national,
regional and transnational scales that seek to balance long-term water needs, essential ecological
processes and economic gains.
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Box 9.6: Payment for Watershed Services
The ecosystem services delivered by a particular geographical location and habitat will provide
benefit both to the location itself and to others at a distance. In current market conditions and governance structures, the costs of protecting these ecosystem services, in terms of proactive management
or lost opportunities to carry out other activities, falls predominantly on those in the provider location. It is thus important when considering the ecosystem service of an area to identify the flows of
benefits, so that the full value, in ecological terms, can be assessed. So, for example, forests provide
services at the global level (regulating climate, sequestering and storing carbon dioxide, biodiversity,
as a source of medicinal plants), at the national/regional level (e.g., timber resources, opportunities
for eco-tourism), at the river basin level (e.g., clean water, regulated river flows (less floods, higher
dry season flows), reduced sediment supply) and at the local level (e.g., timber, firewood, water,
non-timber forest products).
Forests in many areas of the world are under pressure primarily due to the clearance of land for
food production or timber extraction. There is much evidence that such activities cause the loss of a
whole range of ecosystem services at all levels from global to local. Therefore, it is argued that those
who would benefit from the protection of such services should contribute financially to their protection. This is one of the underlying principles of the global carbon market (although this also allows
swapping of damaging behavior in one location for carbon storing actions in another). The idea
of ecosystem service beneficiaries paying managers of the land elsewhere to protect those services
either proactively, or through not taking some action (such as forest clearance for agriculture) is the
concept behind payment for Environmental services (PES)(see also chapter 8 on PES in this report).
At the watershed, or river basin level, this is often called payment for watershed services (PWS),
although it can be argued that this is only a partial picture of the services delivered predominantly
through transfers of water and mass (sediment, nutrients, contaminants).
It is now recognized globally that with ever increasing population and standards of living, the environmental resources of the planet are becoming stretched to, and sometimes, beyond, their limit;
climate change is the obvious pressing example. Many governments, NGOs and scientists are now
starting to advocate ecosystem approaches and PES schemes to protect and restore the environment
to address such concerns.
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